This invention relates to axle beams for vehicles, and more particularly, the invention relates to axle beams suitable for the front axle of a vehicle.
Solid formed or cast axle beams have been used for the front axle of vehicles. The solid axle beams provide a durable structure capable of withstanding the bending and torsional loads to which it is subjected. However, solid axle beams are rather heavy thereby adding weight to the vehicle. Furthermore, there are areas on the axle beam that are subjected to less bending and torsional forces, and therefore, need not be as robust as the rest of the axle beam.
Hollow axle beams have been developed which provide the potential for reducing the weight of the axle beam. Starting from a blank or tube with constant wall thickness, the axle beam may be formed with various cross-sectional shapes to better withstand the bending or torsional forces in a particular area. For example, a hollow torsional beam has been developed using a hydroforming process. However, other processes may be desirable to form a hollow axle beam.
To further control the weight and provide structural integrity which varies with the forces in a particular area of the axle beam, a variable wall-thickness axle beam has been developed. Tubes of various lengths are welded from end to end and then formed into the desired axle beam shape. As a result, the different tubular sections must be aligned properly prior to welding.
Therefore, what is needed is an improved tubular axle beam apparatus and method for forming hollow beams.
The present invention provides a tubular axle beam with variable wall thickness, for a vehicle including a first beam portion extending longitudinally between first ends and including spaced apart first longitudinal edges. A second beam portion extends longitudinally between second ends and includes spaced apart second longitudinal edges. Weld beads secure the first longitudinal edges to the second longitudinal edges to define a cavity between the beam portions with the first and second ends arranged adjacent to one another. Preferably, the tubular axle beam is constructed by stamping a first blank to form a first half of the beam, and a second blank is stamped to form a second half of the beam. The first and second portions are welded to one another to define a cavity between the portions. The blank with variable wall thickness is tailored to eliminate weight in areas showing low stress.
In another embodiment of the invention, a tubular axle beam includes a hollow beam extending longitudinally between opposing ends. A reinforcing sleeve is arranged concentric to the hollow beam between the ends with the reinforcing sleeve secured to the hollow beam, preferably, by weld beads. The hollow beam and reinforcing sleeve initially may be cylindrical tubes that are secured to one another. Subsequently the hollow beam and reinforcing sleeve may be bent into a desired shape and then further formed using a hydroforming or other process to obtain cross-sectional areas of various shapes along the length of the beam.
Accordingly, the present invention provides an improved tubular axle beam apparatus and method for forming hollow beams.